Although the role of zinc in the growth of microorganisms, plants, and animals was well established many decades ago, its role in humans was first recognized only in 1963 [1]. Our studies from the Middle East showed, for the first time, that zinc deficiency occurs in humans [1]. In 1974, the Food and Nutrition Board of the National Research Council of the National Academy of Sciences [2] made a landmark decision to establish a recommended dietary allowance for zinc as an essential element for humans.